What is the importance of the speed of a Compact Flash Card? I believe it refers to the speed at which data is passed to the card?I see ads for "High Speed Memory Cards" Does it refer to the speed at which photos are transferred to computers or does it refer to a photo of a fast moving object transferred to the card?

For example, I have 4GB card that has a speed 15MB and an 8GB card with a speed of 60MB

As a general rule, the "speed" of a CF card is _mostly_ based on the speed that your camera can write to it. The speed that you can read back from it tends to be comparable, yet of different importance. Some fast cards are rated as "UDMA" and they are about as fast as anything I've seen. Some cameras are so old and their CF card interface is so slow that there is no point in investing in super-fast CF cards. On the other hand, many of the very newest cameras are so good that they can really haul with the UDMA-rated cards. If you name your camera model, somebody can probably suggest whether it can get the good out of slow, medium, or fast cards.

Eight years ago, my oldest camera then could only get the good out of a 4X card. Now, my newest camera can get the good out of a 300X UDMA card.

The term "High Speed Memory Cards" is pretty meaningless these days. I think it means anything faster than mag tape.

DPReview typically has a speed comparison of some of the CF cards on the market.

There are all sorts of confusing terms. A "fast lens" has nothing to do with velocity.

Hi FrankThis article will be of interest to you :http://www.molon.de/E620/writetime/BTW, the read/write speed (100/200x ...) is compared to the write speed of a floppy disk (ask grandad about those)Franco

A camera that shoots faster continuously is important to my photography, so I keep CF cards mostly at 233X to 300X.

Few people with cameras need that much firepower, so they can purchase slower CF cards (cheaper) and do nicely. Many people are looking for smaller and smaller cameras these days, so the physical size of a CF card is forcing manufacturers into the smaller form factor memory cards.

"or does it refer to a photo of a fast moving object transferred to the card?"

If you are trying to photograph a fast moving object, the primary thing that allows that is the camera's shutter speed, like 1/1000 or 1/4000 (second). To support the camera shooting that fast, it is helpful to have a lens with a relatively wide open aperture (low f-stop number) and also a camera that can shoot with a relatively high ISO number and still keep the color noise tolerable. Most modern cameras can do that to some extent. Also, in the technique category, it is helpful to be able to pan the shot (swing the camera as the target moves across the field laterally), and there are some support items that can help that. There are ways for a strobe flash to freeze action also.

Instead, some shooters prefer to hold the camera more stationary and to simply fire continuously. They let the target "walk in" to the frame, and one of them will be the perfect image. Some modern cameras can handle large continuous shooting rates, and they have large buffers to hold lots of shots until they can be written to the memory card. A few cameras can be shot continuously at a high rate (JPEG format) and write fast enough that they are virtually unlimited until you fill the CF card.

I have an E-620 and have used an old 512MB card (c. 2004) and a new SanDisk Ultra 30mb/s card. The Ultra card is faster, maybe by 20% (enough to be noticeable) at single-shot superfine resolution. The point being that 60mb/s is probably not noticeably faster than 15mb, and is legitimately faster only in the card manufacturer's lab.

BTW, the strobe feature is terribly annoying and rarely works. (It's probably the only DSLR--make that the only 21st century digital camera--that lacks an IR (red eye) emitter for low-light autofocusing.) A much better strategy is via MF, and you can assign the Fn button to switch between MF and AF on-the-fly. Sometimes the AF sensor will work for the first shot, then crap out; but if you switch to MF after the first shot (and don't change the distance to the subject) you can continue shooting--and quite fast (no AF lag). Just remember to turn AF back on...

"(It's probably the only DSLR--make that the only 21st century digital camera--that lacks an IR (red eye) emitter for low-light autofocusing.)"

Simon, that is an interesting statement. It is wrong.

Let's take Canon DSLR cameras as an example of modern models. Five or ten years ago, the low-light autofocus assist lamp was a Red/Infrared emitter. Then it was decided to be unnecessary. Now, the popup flash is "strobed" or "flickered" to produce normal spectrum flash light. It works good and lasts a long time.